Extraction equilibrium of beryllium and aluminum and recovery of beryllium from Egyptian beryl solution using CYANEX 921

Abstract

Extraction of Be(II) and Al(III) from aqueous sulfate solution by CYANEX 921 (commercial trioctylphospine oxide) in kerosene was separately studied. The parameters affecting the extraction process, such as hydrogen ion, sulfate ion, and CYANEX 921 concentrations, and temperature were investigated. It was found that Be(II) was highly extracted by CYANEX 921 from an aqueous medium of 0.001 M sulfate and pH 9.0, while Al(III) was highly extracted from a similar solution at pH 5.0. Be(II) extraction was found to decrease with temperature (exothermic), while Al(III) extraction increased with temperature (endothermic). The different species that might be extracted are given and discussed. Extraction of Be(II) and Al(III) by purified TOPO under similar experimental conditions showed that purified TOPO gives relatively less extraction, especially for Al(III) in the pH range 4.0–6.0. Based on the obtained results, separation of beryllium from aluminum and recovery of pure beryllium from beryl mineral were studied. Removal of iron as the main interfering ion in the beryl solution was investigated. A flow chart for the Be/Al separation process was developed and applied to recover pure Be(II) from Egyptian beryl.